(1) Field of the Invention
This invention is concerned with apparatus for heating shoe parts whereby adhesive on a surface of such parts can be activated, said apparatus comprising a heater arranged to emit infra-red radiation and having a continuous heating surface which is of an area greater than that of the shoe part to be heated, said surface being maintained at operating temperature, when the apparatus is in use, not only during an operating cycle but also between successive cycles, a support for supporting a shoe part to be heated, and drive means for effecting relative movement between the heater and the support, in a first direction to bring the heater and support into an opposed relationship, in which a shoe part supported by the support can be heated by the heater, and in a return direction to move the heater and support out of such opposed relationship.
(2) Prior Art
By using an infra-red heater having a continuous heating surface of area greater than that of the shoe part to be heated, it is possible more readily to control the amount of heat to which the shoe part is to be subjected, and thus to control more accurately than has previously been the case the amount of time required to activate the adhesive coating on the surface of the shoe part. In practice, it has been found that an operating time of between 4 and 8 seconds, preferably 6 seconds is adequate for activating the adhesive.
Apparatus of the type referred to are suitable for use in combination with a so-called cement sole attaching machine, in the operation of which shoe sole units are secured by adhesive to bottoms of lasted shoe uppers. Thus, the operator takes a shoe sole unit and a lasted shoe upper, with the adhesive coatings on one or both parts activated using the subject apparatus, and assembles the parts in a desired relationship prior to inserting them into the cement sole attaching machine. The total cycle time for this latter machine is, however, somewhat longer than the operating cycle time for the apparatus.
With other apparatus used for heating shoe parts, e.g. in preparation for cement sole attaching operation, it is customary either to switch off the heat after a desired period, or it has been suggested to reduce the heat output by a half, so that the adhesive is not subjected to excessive heating during the intervening period before it is assembled as aforesaid. With certain adhesives, however, only a relatively restricted amount of time after activation is available for carrying out the bonding operation, and in any event, in the case of any adhesive it is usually at an optimum stage for use in the bonding operation immediately at the end of the heating operation.
It is consequently the object of the present invention to provide an improved apparatus for heating shoe parts, wherein the bringing of an adhesive coating thereon to its optimum condition for the subsequent bonding operation can be set so as substantially to coincide with the operator being ready to utilize the part in such bonding operation.